1. Field of the Invention
The present invention relates to concrete works, such as gravity dams and, more particularly, to a sealing device for sealing expansion joints cut in dams of this type.
2. Description of the Prior Art
Concrete dams, either gravity dams, arched dams, or even dams with joints can suffer from behavioral problems such as, for jointless dams, the fissuring of the dam due to stresses, or the inflation of the dam caused, for instance, by chemical reactions in the dam. In the case of the dams having joints, it happens that the joints leak.
For repairing concrete dams so affected, a joint must be produced for preventing the transmission of the stresses, for diminishing the inner stresses and for providing space for the ulterior volume increase of the concrete. The methods actually known are complicated and very costly. The section to cut necessitates first the construction of a coffer-dam on the wet side or upstream of the dam which has the height of the dam for preventing the flow of water through the cut during the repairs. Such a coffer-dam is subject to very high pressures whereby it represents security problems which are partially resolved by a very costly installation. The repairs must be done by divers and even by divers in diving suits depending on the depths. Also, it is necessary to continuously pump water which infiltrates the coffer-dam. The repairs of concrete dams using this method are thus very costly. Once the repairs are completed, it is very advantageous to replace the coffer-dam by a sealing device. To date, there does not exist any known device of this type of long-term efficiency.
To offer expansion joints to concrete dams, certain tests have been made with the insertion between the concrete sections of the dam of joints made of plastic materials. However, once flattened by the displacement of the dam, the plastic joint does not recover its initial form when the dam returns to its original position, which results in joints that leak. Also, there is no adherence between the plastic joint and the concrete dam. The use of joints made of caulking would produce the same results since these joints would dry up after one or two years.
To produce expansion joints in concrete dams, it has also been proposed to construct the dams with a plurality of distinct sections which are nested and separated by an empty space which acts as a play during the displacements of the various sections of the dams. Each section of the dam is coffered independently with a spaced nesting for producing the joint. For sealing the extremity of the joint located upstream, sealing plates are installed which adjust when the sections of the dam shift one with respect to the other in order that the dam maintains its water tight feature. As the spaces between the various sections of the dam which serve as joints become filled in due time with limestone and others, the gaps become filled, thereby eliminating the play between the sections of the dam and consequently the expansion joint itself.